Yves-Bernard André: Kind of Blue
Yves-Bernard André: Yes, it is quite interesting that in adding some noise to the signal, we can actually get more information back.
Scull: How do you implement that in the CD 1?
André: We have a main diode that reads the information in the normal fashion. And a blue-laser diode that is giving atmosphere of light to the other laser, if you like.
Scull: The blue laser bathes the underside of the CD?
Scull: Which adds a type of noise?
André: Exactly. But you don't hear this noise when you listen...
Ariane Moran: No...it's optical noise.
André: It permits the recovery of some information whose energy was not sufficient...
Scull: To drive a zero to a one or the other way around?
André: Exactly. Let me explain it this way. You take a box of eggs and you "shake" it with a soundwave. But the energy is not totally sufficient that an egg moves from one hole to another. If you look, you have no signal, because the eggs are not moving. Then you add stochastic noise. The energy of this noise is sufficient to permit the egg to move from one hole to another. And at this time you don't see the noise, but you see the signal, which existed before.
Scull: Leaving the chicken coop for the lab, how does that translate into the CD 1's operation?
André: We decided that the LSBthe Least Significant Bitwas a very important consideration. Here are two levels: the noise of the LSB, which is dither, and the noise we add with the blue laser in the analog domain. We apply the lightthe treatmentas the laser reads the data, while dither is added afterward, of course.
Scull: What did you hear when you first tried it?
André: I was simply amazed, because I was getting more information, more sweet information. It sounded continuous, like music, with more harmonics. In the analog domain, you know, noise decreases slowly, continuously, so that even under the noise floor it is possible to retrieve some information. But with digital, under the LSB, there is no more information! A disaster. Not very natural-sounding at all.
Scull: Uh-hum...so all your existing customer units are upgradeable to the blue laser?
Scull: And you recommend that, no doubt.